Arches or top chord construction



Aug. 9, 1949. i A. v. PEDERSEN 7 2,478,421

ARCHES 0R TOP CHORD CONSTRUCTION Filed Jan. 30, 1947 [77 vemok A XEL 1/. PEDEHSEN 5M fia wm 77 Aftor'neys 1 Patented Aug. 9, 1949 UNITED STATES PATENT OFFICE ARGHES OR TOP CHORD CONSTRUCTION Axel V. Pedersen, Los Angeles, Calif.

Application January 30, 1947, Serial No. 725,306

3 Claims. 1

This invention relates to improvements in generally arcuate wooden structural elements such as arches, the top chord of trusses and similar structures. It may be regarded as a further development of the construction disclosed in my copending application, Serial No. 516,067, filed December 29, 1943, now abandoned.

An object of the present invention is to provide an arch or similarly curved structure which is formed of a plurality of wooden elements such as heavy boards wherein these elements are arranged in end-tmend relationship with their lengths at slight angular relationship to each other to generally conform to the curvature of the structural elements and characterized by the fact that there is a novel, simple, and advantageous joint between the adjacent ends of adjacent elements.

With the foregoing and other objects in view, which will be made manifest in the following detailed description and specifically pointed out in the appended claims, reference is had to the accompanying drawings for an illustrative embodiment of the invention, wherein:

Figure l is a view in side elevation of a portion of an arch or curved structural element embodying the present invention; and

Fig. 2 is a perspective view illustrating the adjacent ends of adjacent elements in spaced relation to each other.

Referring to the accompanying drawings wherein similar reference characters designate similar parts throughout, the arch illustrated in Fig. 1 is composed of a series of boards ill arranged in end-to-end relationship to each other and having their lengths at a slight angular relationship to each other so that collectively the entire structure formed by these elements generally conforms to the curvature of the desired arch. Each element 18 has on both ends thereof two oppositely scarfed tenons, Thus as illustrated in Fig. 2 the element lea has an upper tenon II scarfed from the forward side of the element to the rear side thereof. It also has a lower tenon l2 which is scarfed from the rear side to the forward side. These tenons are of approximately equal length and have their outer ends arranged to terminate approximately in the same transverse plane. In a similar manner the element lflb has an upper tenon it which is scarfed from the rear side of the element to the forward side and a lower tenon l that is scarfed from the forward side to the rear side thereof. The tenons l3 and M. are counterparts of the tenons l I and 12 so that when 2 they are assembled together the scarfed faces will fit snugly against each other.

The adjacent edges of the tenons II and I2 are arranged at a slight angle to the length of the element lfia so that the shoulders or faces indicated at I5 and I6 are in a plane across the thickness of the element 10a and slightly inclined to the length thereof. In a similar manner the adjacent faces or edges that form the corresponding shoulders at the sides of the tenons I3 and 14 are inclined slightly to the length of the element Nib. Thus if the center line of one element is represented by the line AB and the center line of an adjoining element is represented by the line C-D, and the acute angle between these center lines is 10 the inclination of the faces or shoulders l5 and (6 with respect to the center line A-B would be approximately 5'. Likewise the acute angle between the faces or shoulders at the sides of the tenons l3 and I4 would be approximately 5 to the center line C-D. The upper or outside corners of the tenons I! and it are bevelled off to remove the portions indicated by dotted lines at I! and I8 on Fig. 1 although this is not essential unless a relatively smooth outer surface of the arch is desired.

By constructing an arch or similar curved structural element in this manner all of the elements may be shaped at a wood-working plant and shipped as such to the location where the arch is to be constructed. They may there be assembled in the manner indicated and at the time of assembly glue or other adhesive is applied to the abutting faces on the ends of all of the elements. The slope of the scarfs may vary but should be materially greater than the slope of 1:1. A slope in the neighborhood of 1:10 is generally desirable. As such a slope causes the tenons by means of their mutual engagement to be capable of transmitting bending stresses across the thickness of the joint produced thereby, the mutually engaging shoulders or faces indicated at 15 and IS on the element Illa and the corresponding shoulders or faces on the element [0b tend to transmit bending stresses across the joint in the plane of the height of the elements. Consequently the glue or adhesive is not required to carry any substantial stress and is utilized mainly for the purpose of permanently fastening the elements together,

If the span of the arch is known and the number of elements I 0 that are to be assembled therein is likewise determined then the required angular relationship between the lengths of the center lines AB and 0-D can be readily determined. When this angular relationship is thus known or determined the-angle of the faces l and IS on the tenons to the center line AB is arrived at by dividing the angle between the center lines AB and CD in half. Consequently it is relatively easy to set up a jig or fixture that will enable these tenons to be accurately cut at a wood-working plant to their being assembled or shipped to the point of assembly, When the elements are assembled together they cooperatively form a generally curved structure which is advantageous in that the boards or elements are positioned in a vertical plane across the arch and the joints are so constructed as to carry both lateral as well as vertical bending moments.

From the above-described construction it will be appreciated that by so shaping the tenons that the adjacent faces on the sides thereof indicated at l5 and IE or at a slight angle to the center line of the element that a curved structural element can be easily assembled and constructed.

Various changes may be made in the details of construction without departing from the spirit and scope of the invention as defined by the appended claims.

I claim:

1. An arcuate structural element including a plurality of wooden elements arranged in end-toend relationship with their lengths at a slight angular relationship to each other, each element having at least two oppositely scaried tenons at each end thereof which fit against the tenons of adjacent elements, the adjacent sides of the tenons on each end of each element being inclined to the length of the element at an angle equal to approximately one-half of the angle between the elements of adjacent elements.

2. A wooden element, a plurality of which may be assembled to form a generally arcuate structure, said Wooden element being substantially straight and having at each end thereof oppositely scarfed tenons, the adjacent sides of the tenons being arranged at an angle to the length of the element.

3. A wooden element, a plurality of which may be assembled to form a generally arcuate struc ture, said wooden element being substantially straight and having at each end thereof oppositely scarfed tenons, the adjacent sides of the tenons being arranged at an angle to the length of the element, that tenon which is to be disposed outermost in forming the arcuate structure being partially bevelled ofi".

AXEL V. PEDERSEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 53,495 Shenton Mar. 2'7, 1866 218,920 Bramble Aug. 26, 1879 2,409,383 Pedersen Oct. 15, 1946 

